Study On A Big Circular Ring Linear Induction Motor

Linear induction motor is an important kind of machines which have some merits such as simple structure, low cost, durability, convenience for maintenance etc. The subject of this thesis is to study a big circular ring linear induction motor, and the major works in this thesis are summarized as follows:(1) Considering the effects of the finite length of primary core, one-dimension analytical solution for the air gap field is cited in this paper. Based on it, the single layer winding magnetic field is studied. Considering whole-pitched and short-pitched winding configuration with odd poles and half-fulled slots in both ends, the double-layer winding magnetic field is analyzed, respectively. Besides, two-dimension analytical solution is also simply introduced.(2) A software of the Finite Element Method is employed to analyze the stationary magnetic field distribution in the air-gap of the motor and the calculable results are discussed.(3) The software of the Finite Element Method is also applied to calculate the transient behaviour of the motor under the rated voltage. The relations of torque, displacement, speed vs time are obtained, respectively. The speed is measured by a hall element and is compared with computation value. The maximum electromagnetic force during the rotor locked is obtained by the equivalent circuit method. The correctness of the presented method is verified by the experiments. Three-phase current waveforms are obtained by the experiments and are compared with computations, and its asymmetry about three-phase currents is analyzed.